The transcript is for your convenience So, the prime factorization of 18 – 18 is even, so it’s divisible by 2, so 2*9 would be 18, 9 is not prime nos., so we need to break 9 down, and the factors of 9 are 3*3. So, the prime factorization of 18 would be 2*3*3.

3*3 is 9, times 2 is 18. I always like to check after I factor to make sure I’ve got it.

The prime factorization of 30 – 30 is divisible by 2 also, since it’s even, so 2*15 would be 30, but 15 is not prime, so we have to break it down into its prime factors, and 15’s prime factors are 3*5. So, the prime factorization of 30 is 2*3*5. 2*3 is 6, and 6*5 is 30.

Now, again, to find the GCF, we’re going to look for what they have in common. 18 and 30 have 2 and 3 in common as prime factors.

So, we take those factors they have in common and multiply them. 2*3 is 6, so the GCF of 18 and 30 is 6. 6 is the largest factor that these numbers have in common.